<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <button>清除</button>
  <script>
    var btn = document.querySelector('button')

    var timer = setTimeout(function() {
      console.log('炸了')
    }, 3000)

    btn.onclick = function() {
      clearTimeout(timer)
    }
  </script>
</body>
</html>